1. Field of the Invention
The present invention relates to apparatus used in the cutting and breaking of bones in certain medical procedures.
2. Description of the Related Art
Certain medical procedures require the surgeon to break a bone. Examples of these procedures are bone lengthening operations that require the insertion of a bone lengthening device or other prosthesis. The conventional manner of performing this operation usually requires removing the bone marrow in the center of the bone by drilling through one end of the bone down its longitudinal axis to create a cavity in the bone marrow in which the bone lengthening nail or prosthesis is to be fit.
After this cavity has been drilled, holes are generally drilled perpendicular to the bone at the site where the bone is to be broken. Once the holes are drilled, a chisel is inserted into this region and driven through the bone section and twisted to cause the bone section to break.
The bone lengthening nail is then inserted into the cavity so that the upper portion is lodged in one-half of the broken bone and the lower portion of the nail is lodged in the lower portion of the broken bone. The nail is periodically lengthened in order to lengthen the bone, which heals itself through a knitting process. This bone breaking procedure is an excessively invasive procedure, requiring drilling the holes in the bone and inserting the chisel blade to actually create the fracture.
Moreover, fractures made by this procedure tend to be irregular and fragmented, making the bone more difficult to realign once the bone lengthening device is inserted into the bone marrow cavity.
Thus, there is a need for a bone breaking apparatus that will provide an internally-created cut or stress concentration so that the resulting bone break is regular and easy to realign once a bone lengthening device is inserted into the cavity.
In an alternative procedure, a bone saw is placed within the bone marrow cavity and the bone cut radially from within. However, the cutting depth cannot be controlled so that the depth of the cut can vary according to the thickness of the bone. Therefore, a single cut of uniform depth is made, where the depth of the cut is limited by the thinnest portion of the bone in order to prevent damaging the periosteum and surrounding soft tissue at the thinnest point by cutting deeper. While the thinnest portion of the bone may be cut completely through, there are other areas which are only partially cut. Additionally, this type of saw is incapable of cutting the bone along its length.
Further, such bone saws cannot be used for cutting the femur head due to their large size and limited angular motion. In particular, features such as air inlet and exhaust hoses limit the angle to which the cutter head can be moved.
To overcome the disadvantages of the prior art, and in accordance with the purposes of the invention, as embodied and broadly described in the application, the invention provides a method of cutting a bone using a bone cutting apparatus. The method includes determining a first cutting depth based on variations in radial bone thickness of the bone, inserting a bone cutting apparatus having a cutting blade into a hollow space within the bone, moving the cutting blade radially to set it to the first cutting depth, cutting the bone at the first cutting depth, determining a second cutting depth based on variations in the radial bone thickness, adjusting the cutting blade radially to set it to the second cutting depth, and cutting the bone at the second cutting depth.
According to another aspect of the present invention, a bone cutting apparatus is provided. The bone cutting apparatus includes a power source, an articulating cutting assembly connected to the power source and having a cutting blade, the cutting blade moveable between a stored position and a cutting position, a cutting guide for guiding the cutting blade during bone cutting; and means for locking the bone cutting apparatus to a bone being cut, wherein at least a portion of the bone cutting apparatus including the cutting assembly is shaped to fit within a cylindrical cavity of a bone.
According to another aspect of the present invention, a powered bone breaking mechanism is provided, comprising a machine spring, a powered spring having a compacted state and an expanded state, the powered spring comprising a shape memory alloy, and a power source connected to the powered spring.
According to one aspect of the present invention, a method of breaking a weakened bone is provided. The method includes attaching a powered bone breaking apparatus to a weakened bone, and moving a powered spring of the apparatus from a compacted state to an expanded state.
According to a further aspect of the present invention, a miniature cutting device is provided. The miniature cutting device comprises a turbine and burr, a spherical turbine support housing, including two hemispherical turbine support housing portions, wherein the turbine support housing portions fit together to form the spherical turbine support housing and to hold the turbine and burr, and wherein a first hemispherical turbine support housing portion includes slots for directing air onto blades of the turbine to rotate the turbine, two outer cutter assembly support housing portions, wherein each hemispherical turbine support housing portion is fitted to a respective outer cutter assembly support housing portion, wherein the outer cutter assembly support housing portion fitted to the first hemispherical turbine support housing includes an air inlet passage for supplying pressurized air to the slots of the first hemispherical turbine support housing, and means for rotating the turbine and burr about a longitudinal axis of the device.
According to yet another aspect of the present invention, a method of removing an interior portion of a femur head is provided. The method comprises creating a small incision into skin below a hip of a patient to expose the femur, drilling a small hole into the femur, inserting a miniaturized femur cutter into the hole in the femur, rotating a turbine and burr of the miniaturized femur cutter at a high speed to cut away a rotting, decayed, or cancerous section of the femur head, changing the cutting angle as necessary by rotating the turbine and burr about a longitudinal axis of the miniaturized femur cutter, and removing the miniaturized femur cutter from the femur.